Bong-Guen Hong

DEVELOPMENT OF A HIGH HEAT FLUX TEST FACILITY FOR PLASMA FACING COMPONENTS

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. One of the major purposes of this facility is to carry out a thermal cycle test of the ITER (International Thermonuclear Experimental Reactor) FWQM (first wall qualification mockup). The facility is equipped with a graphite heating element, a water cooled box-type vacuum chamber, and diagnostic systems. Two mockups are installed in the chamber; two facing mockups are simultaneously heated by a graphite heater installed between two mockups. The graphite heating element has an effective irradiation area of 244 mm × 80 mm and its electrical power is provided by a 40 kW DC power supply. The diagnostic system consists of two independent calorimetric power measuring systems, thermocouples, a vacuum gauge, and a CCD camera. Water cooling, Be treatment, and vacuum pumping systems are also equipped. We performed thermal cycle tests for two Cu mockups, and for Cu and Cu/SS mockups ensure the performance of the KoHLT-1. After that, we carried out thermal cycle tests up to 220 cycles for Cu mockup and FWQM at 0.65 MW/m2, from which the reliability of the KoHLT-1 was verified.

Fabrication of prototype ICRF antenna for KSTAR and first RF test

Abstract A prototype ICRF antenna has been fabricated and is being tested for the development of long pulse (300 s), high power ICRF system of KSTAR. The antenna has many cooling channels inside the current strap, Faraday shield, cavity wall and vacuum transmission line to remove the dissipated RF loss power and incoming plasma heat loads. The antenna is installed in the RF test chamber evacuated by 2000 l/s turbomolecular pump and consistency with the design requirement for long pulse, high power operation is being investigated through the RF test. With the half of a current strap connected to the matching circuit via a vacuum feedthrough and a directional coupler, and the other seven ports shorted at the input ports, intermediate RF power test has been performed at f=32 MHz. During the RF pulse, the maximum peak voltage, forward/reflected powers, temperature on the antenna and gas pressure are measured. Even the initial test results promise that the long pulse, high power operation of the ICRF system will be obtainable for the advanced tokamak operation of KSTAR tokamak.

Development of a High Heat Load Test Facility KoHLT-1 for a Testing of Nuclear Fusion Reactor Components

A high heat flux test facility using a graphite heating panel was constructed and is presently in operation at Korea Atomic Energy Research Institute, which is called KoHLT-1. Its major purpose is to carry out a thermal cycle test to verify the integrity of a HIP (hot isostatic pressing) bonded Be mockups which were fabricated for developing HIP joining technology to bond different metals, i.e., Be-to-CuCrZr and CuCrZr-to-SS316L, for the ITER (International Thermonuclear Experimental Reactor) first wall. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical DC power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. The graphite heater is placed between two mockups, and the gap distance between the heater and the mockup is adjusted to . We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups, and to have the electrical resistances of ohms during high temperature operation. The heater is connected to an electrical DC power supply of 100 V/400 A. The heat flux is easily controlled by the pre-programmed control system which consists of a personal computer and a multi function module. The heat fluxes on the two mockups are deduced from the flow rate and the coolant inlet/out temperatures by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups, and the reliability of the KoHLT-1 for long time operation at a high heat flux was verified, and its broad applicability is promising.

Heat flux test of various Be mockups for ITER FW development at Korea heat load test facility KoHLT-1

We established a heat load test facility using a graphite heating panel in 2008 in order to verify the integrity of a HIP bonded first wall. The facility is called KoHLT-1 and is currently in operation to test the Be mockups. The KoHLT-1 consists of a graphite heating panel, a box-type test chamber with water-cooling jackets, an electrical power supply, a water-cooling system, an evacuation system, an He gas system, and some diagnostics, which are equipped in an authorized laboratory with a special ventilation system for the Be treatment. We designed and fabricated several graphite heating panels to have various heating areas depending on the tested mockups. The heat fluxes on the two mockups are independently measured by a calorimetric method. We have carried out the thermal cycle tests of various Be mockups. The nominal heat flux was 0.625 MW/m2 or 1.5 MW/m2 depending on the mockup sizes

Design Characteristics of KT-2 Tokamak for Advanced Tokamak Operation*

Adaptability of the advanced tokamak discharge, i.e., 100% non-inductive current drive with high(> 70%) bootstrap current fraction, in a large-aspect-ratio (LAR), medium-size, diverted tokamak KT-2 [ 1 ] is investigated with the time-dependent transport simulation. Through the dynamic simulation, the stable route to high βp, high bootstrap plasma with negative shear over a central plasma region is found. And the required auxiliary heating and current drive power and design requirements for the advanced tokamak operation are obtained. The compatibility of the advanced tokamak operation mode with the poloidal field coil system and the divertor system is demonstrated.

Design and analysis of the magnet system for the KT-2 tokamak with long-pulse operation capabilities

A large-aspect-ratio diverted midsize tokamak KT-2 are being designed at KAERI. The KT-2 tokamak aims investigations of the advanced tokamak physics issues, thus necessitating steady-state operation capabilities with superconducting magnets. In KT-2, where normal copper magnets with active cooling are employed, this need is circumvented by incorporating long-pulse operation capabilities with minimum 4 to over 19 seconds current/field flattop. In this paper, design principles and baseline design parameters of the TF/PF magnets on the basis of KT-2 operation modes are derived and discussed. Electromagnetic and thermal analysis results are presented, with discussions of key criteria identified for the detailed engineering design which are being carried out presently.

Design of the magnetic system and derivation of the operation modes of the large-aspect-ratio (LAR) tokamak KT-2

A large-aspect-ratio (LAR), midsize, diverted tokamak KT-2 with intense heating (8-10 MW) has entered the construction phase at KAERI. The machine parameters are: R/a=1.4/0.25 m, B/sub t/=3 Tesla, I/sub p/=500+ kA, current flat-top of minimum 4.0 sec at maximum field and current (OH-only). The PF system design resulted in three major KT-2 operation modes. The 5 MW HiBS mode, which utilizes higher bootstrap current fraction, allows extended discharges for >20 sec at 2 T/300 kA. The machine will start operation by the end of 1998.